Photo storage

You have been right to hesitate with the syncing. When you sync an iPad or iPhone or iPod touch with a computer, the previously synced photos will be removed and replaced by the new syncing.

When you sync again, you have to sync all photos together to the device - the previously synced photos together with the additional photos that you want to see on the device..

Do you still have the photos tat are currently on your iPad somewhere on your computer? if not, you should save them somewhere else. But it will be a lot of work to transfer synced photos to a computer, because the manual syncing with iTunes or the Finder is one-way. We cannot download them directly from the device. We have to mail them or save them to Photos before they can be downloaded. The storage on the iPad should not be the only storage. When you sync photos to an iPad or iPhone will be stored only at a slightly reduced resolution, suitable for viewing, but not suitable as a long-term storage and archive of your photos.

You may want to use a 3rd party application to help move files between your computer and iPads. I used the app Imazing for awhile, and it worked well. But they charge by the device ($60 for 3), and I got frustrated when I swapped one iPad for a newer one, and the wanted to charge more even though the first one was wiped. I bet there are others...